Well that's strange. I have another track that begins with a Shape event, where the Data column says 0.80-0.80, the next column says Linear, and the time is way past the end of the song, and MIDI volume control changes work fine in that track, even when moving the Now time around.
I drew a similar horizontal line with a value of 101 in the automation lane in the malfunctioning track, and now it is working correctly. What is the relation of the Volume automation lane and explicit MIDI volume control change events? And what's the difference between a solid line in the automation lane and a dotted line? This is very confusing.